A device embedded substrate is described in Patent Document 1. As described in Patent Document 1, the device embedded substrate is formed by mounting an electric or electronic device on a conduction layer which serves as a conductor pattern, and embedding it in an insulation layer such as a prepreg. When the device is embedded, the device is passed through a perforation of a perforated prepreg and a perforated core material, which are hollowed in a portion corresponding to the relevant device, and a cover prepreg on which no perforation is formed is laminated thereabove and pressed. After lamination, conduction between a terminal and the conduction pattern is achieved by forming a via which is a perforation reaching an electrode terminal included in the device, and plating the inner surface thereof, or by soldering without using a via.
Such a via is typically processed by CO2 laser. In laser processing, power, a pulse width, the number of shots, and the like are specified depending on time and circumstances.
On the other hand, when conduction is desired for both faces (upper and lower faces) of the device, a via which reaches a device terminal is further formed on the opposite face. Then, the via is subjected to a plating process to achieve conduction between the device terminal and the conductor pattern.